Effect of damping of pore water on three dimensional nonlinear seismic response analysis of ground

Three-dimensional nonlinear seismic response analysis of ground was presented in which any special engineering judgment to determine analytical parameters of the ground was not required. To examine the effectiveness of the method, the vertical array strong motions recorded in Kashiwazaki Kariwa Nuclear Power Station during the 2007 Niigata-ken Chuetsuoki earthquake was simulated. When using only hysteresis damping due to shearing deformation in the analysis, the vertical motion showed an excessive response due probably to the resonance of the pore water. When a damping of about 10% was given to the pore water, in contrast, the analysis was able to reproduce the observed three-dimensional ground motion with a reasonable degree of accuracy.